Synthesis and Study of Copper-Containing Polymers Based on Sulfated Arabinogalactan

Synthesis of water-soluble copper-containing sulfates of arabinogalactan was carried out for the first time by the ion exchange method. Their composition and structure were studied by the methods of elemental and chemical analysis, X-ray spectral microanalysis, atomic force microscopy (AFM), infrared spectroscopy (FTIR), and electron paramagnetic resonance (EPR). According to the AFM data, the surface of copper-containing polymer films does not have inclusions and consists of homogeneous crystallites of a spherical and slightly elongated shape and transverse dimensions of about 100 nm. The composition of copper- containing polymers was studied by the chemical method and X-ray spectral microanalysis. The absence of nitrogen in the obtained polymer indicates the complete replacement of ammonium cations in the ammonium salt of AG sulfate with the copper cations. The IR spectrum of copper-containing AG sulfate is similar to that of the sodium salt of sulfated arabinogalactan. Superposition of two signals was observed in the EPR spectrum of copper-containing AG sulfate. One of them belongs to isolated Cu²⁺ ions; another, to associated Cu²⁺ ions in the salt-like compounds. The integral intensity of isolated Cu²⁺ ion signals (anisotropic signal) and associated ions (isotropic signal) depends on the copper content in the polymer. Water-soluble coppercontaining polymers of AG sulfates have prospects for their use in medicine.     

Infrared absorption and raman scattering of sulfate groups of heparin and related glycosaminoglycans in aqueous solution

The i.r. spectra for aqueous solutions of sulfated glycosaminoglycans and model compounds in the transmittance “window” region of the solvent (1400-950 cm^?1) are dominated by the strong and complex absorption centered at ～1230 cm^?1 and associated with the antisymmetric stretching vibrations of the SO groups. Primary and secondary O-sulfate groups absorb at somewhat higher frequencies (1260-1200 cm^?1) than N-sulfates (～1185 cm^?1). Each sulfate band lends itself to quantitative applications, especially within a given class of sulfated polysaccharide. Laser-Raman spectra of heparin and model compounds have been obtained in aqueous solution and in the solid state. The most-prominent Raman peak (at ～1060 cm^?1) is attributable to the symmetrical vibration of the SO groups, with N-sulfates emitting at somewhat lower frequencies (～1040 cm^?1) than O-sulfates. The Raman pattern in the 950-800 cm^?1 region (currently used in the i.r. for distinguishing between types of sulfate groups) also involves vibrations that are not localized only in the COS bonds.     

Raman spectroscopic analysis of the sodium salt of kappa-carrageenan and related compounds in solution

Laser-Raman spectra of Na⁺ kappa-carrageenan, Na⁺ neocarrabiose 4-sulphate, and neocarrabiose in the region 700–1500 cm⁻¹ are reported for solutions in H₂O and D₂O. The C-1-H-1α vibration, coupled with COH related modes, is assigned to a band at 840 cm⁻¹, close to the maximum of the symmetrical COS stretching (∼850 cm⁻¹). The symmetrical SO stretch is proposed to occur near 1040 cm⁻¹ and is probably coupled with COH vibrations which give rise to strong bands in the region 1000–1100 cm⁻¹. The intense band in the region 730–740 cm⁻¹ is ascribed to a complex ring vibration.     

Rheology and composition of a multi-utility exopolymer from a desert borne cyanobacterium Anabaena variabilis

The desert cyanobacterium Anabaena variabilis produces an exopolymer during the stationary growth phase in batch culture. Optimal polymer production was observed at pH?10 under phosphorus limitation. Chemical analysis showed it to be composed of 49% carbohydrate and 19% protein. Monosaccharide analysis revealed a heteropolysaccharidic nature with glucose, mannose, and galactose as the main neutral sugars. Infrared (IR) spectrum of the exopolymer showed absorption bands at 1,645 and 1,421?cm^?1 characteristic of C=O in the carboxylate group. Strong band was observed at 1,072?cm^?1 due to C–O–C or C–O–P stretching vibrations. A band at 2,363?cm^?1 corresponding to C–H stretch of protein was also observed. IR spectrum suggested that the exopolymer is nonsulfated. Rheological properties of the polymer showed marked shear thinning non-Newtonian behavior in the concentration range of 0.1–0.4%. However, it appeared to undergo change in the internal structure on shearing thereby exhibiting thixotropic behavior. The polymer possessed 75% flocculating ability vis a vis alum, 71% emulsification of hexadecane, and good thermal stability making it a potent candidate for multiple industrial applications. The exopolymer bound 156?g H₂O g^?1 and exhibited antibacterial activity against Staphylococcus aureus suggesting a potential for application in wound management as well.     

Synchrotron Fourier-Transform Infrared Microspectroscopy: Characterization of in vitro polarized tumor-associated macrophages stimulated by the secretome of inflammatory and non-inflammatory breast cancer cells

Studies suggested that the pathogenesis of inflammatory breast cancer (IBC) is related to inflammatory manifestations accompanied by specific cellular and molecular mechanisms in the IBC tumor microenvironment (TME). IBC is characterized by significantly higher infiltration of tumor-associated macrophages (TAMs) that contribute to its metastatic process via secreting many cytokines such as TNF, IL-6, IL-8, and IL-10 that enhance invasion and angiogenesis. Thus, there is a need to first understand how IBC-TME modulates the polarization of TAMs to better understand the role of TAMs in IBC. Herein, we used gene expression signature and Synchrotron Fourier-Transform Infrared Microspectroscopy (SR-μFTIR) to study the molecular and biochemical changes, respectively of in vitro polarized TAMs stimulated by the secretome of IBC and non-IBC cells. The gene expression signature showed significant differences in the macrophage's polarization-related genes between stimulated TAMs. FTIR spectra showed absorption bands in the region of 1700–1500 cm^?1 attributed to the amide I ν(C=O), & ν_AS (CN), δ (NH), and amide II ν(CN), δ (NH) proteins bands. Moreover, three peaks of different intensities and areas were detected in the lipid region of the νCH₂ and νCH₃ stretching modes positioned within the 3000–2800 cm^?1 range. The PCA analysis for the second derivative spectra of the amide regions discriminates between stimulated IBC and non-IBC TAMs. This study showed that IBC and non-IBC TMEs differentially modulate the polarization of TAMs and SR-μFTIR can determine these biochemical changes which will help to better understand the potential role of TAMs in IBC.     

Photoluminescence and structural analysis of trivalent europium doped MLaAl3O7 (M = Ba,Ca, Mg and Sr) nanophosphors

The solution combustion technique was used to synthesize MLaAl₃O₇ (M = Ba, Ca, Mg, and Sr) nanophosphors‐doped with Eu³⁺ using metal nitrates as precursors. The photoluminescence (PL) emission spectra exhibited three peaks at 587–591, 610–616, and 653–654 corresponding to ⁵D₀→⁷F₁, ⁵D₀→⁷F₂, and ⁵D₀→⁷F₃ transitions, respectively. Upon excitation at 254 nm, these nanophosphors displayed strong red emission with the dominant peak attributed to the ⁵D₀→⁷F₂ transition of Eu³⁺. The materials were further heated at 900 and 1050°C for 2 h to examine the consequence of temperature on crystal lattice and PL emission intensity. X‐ray diffraction (XRD) analysis proved that all the synthesized materials were of a crystalline nature. CaLaAl₃O₇ material has a tetragonal crystal structure with space group P421m. Scherer's equation was used to calculate the crystallite size of synthesized phosphors using XRD data. A Fourier transformation infrared study was used to observe the stretching vibrations of metal–oxygen bonds. Infrared peaks for stretching vibrations corresponding to lanthanum–oxygen and aluminium–oxygen bonds were found at 582 and 777 cm^–1 respectively for CaLaAl₃O₇ phosphor material. Transmission electron microscopy images were used to determine the size of particles (18–37 nm for the as‐prepared materials) and also to analyze the three‐dimensional view of these materials. The experimental data indicate that these materials may be promising red‐emitting nanophosphors for use in white light‐emitting diodes.     

Structural features and bioactivities of the chitosan

Fourier transform infrared (FT-IR) spectroscopic studies (3500-600 cm⁻¹) showed some different bands of chitosan. The absorption at 3439 cm⁻¹ is stretching vibration of -OH and -NH₂ bonds, indicating the association of the hydrogen-bond between them. The bands at 1659, 1599 and 1321 cm⁻¹ are attributable to the peaks of stretching vibrations of amide I (ν_(CO)), II (δ_(N-H)), and the peak of stretching and bending vibrations of III (ν_(C-N)) (δ_(N-H)). The chitosan showed strong free radical scavenging activities. Pretreatment with chitosan significantly prevented the decrease of antioxidant enzymes activities and the increase of p-JNK at 3 h after renal ischemia and reduced renal tubular epithelial cell apoptosis.     

DNA-Carbohydrate Interaction. The Effects of Mono- and Disaccharides on the Solution Structure of Calf-Thymus DNA

Abstract

We report the interaction of calf-thymus DNA with D-glucose, D-fructose, D-galactose and sucrose in aqueous solution at physiological pH with sugar/DNA(P)(P=phosphate) molar ratios (r) of 1/10,1/5,1,5 and 10. FTIR difference spectroscopy was used to characterize the nature of sugar-DNA interaction and correlations between spectral changes and structural variations for both sugar and DNA complexes have been established.

FTIR difference spectroscopic results showed major sugar interaction (H-bonding) with the P0₂ groups of the backbone at low sugar concentrations (r= 1/10 and 1/5). Such interaction was characterized by the shift and the intensity variations of the backbone P0₂ antisymmetric stretch at 1222 cm^?1, which resulted in a major helical stability of DNA duplex. As sugar concentration increased, carbohydrate binding to DNA bases occurred. Evidence for this comes from major shiftings of the sugar O-H stretching vibrations at 3500–3200 cm^?1, and sugar C-O stretches and OH bending modes at 1450–1000 cm”. Similarly, shifting and intensity variations of several DNA in-plane vibrations at 1717 (G,T), 1663 (T,G,A,C) and 1492 cm^?1 (C,G) were observed, that are characterized by the presence of sugar-base interaction (via H₂0). The shiftings and the intensity changes of the sugar OH stretching modes at 35003200 cm^?1 are also indicative of the rearrangements of the sugar intermolecular H-bonding network, on DNA complex formation. A partial B to A conformational transition was observed for DNA molecule on sugar complexation, whereas carbohydrate binding occurred via both a- and β-anomeric structures.     

Role of Li+ ions on the surface morphology and thermoluminescence properties of Y2O3:Tm3+ nanophosphor

Y₂O₃:Tm³⁺ and Li⁺ co‐doped Y₂O₃:Tm³⁺ nanopowders were synthesized using the solution combustion method for possible application in ultraviolet (UV) light dosimetry. X‐ray diffraction revealed the crystallite sizes to be in the range 21–44 nm and 30–121 nm using the Scherrer equation and the W‐H plot relationship, respectively. Field emission scanning electron microscopy confirmed that, after co‐doping with 4 mol% concentration of Li⁺, the particles were spherical in nature with an average size of ~30 nm. Fourier transformed infrared spectroscopy results showed bands at wavenumbers of 556, 1499, 1704, 2342, 2358, 2973, 3433, and 3610 cm^?1 that corresponded to the stretching and bending vibrations of Y–O, C=O and O–H. Thermoluminescence (TL) glow peaks for Y₂O₃:Tm³⁺ nanophosphors observed at 399 and 590 K were attributed to oxygen defects caused using UV irradiation. These oxygen defects firstly resulted in an increased prominent peak TL intensity for up to 270 min of irradiation and then a decrease. This was attributed to the presence of oxygen defect clusters that caused a reduction in recombination centres. The Li⁺ co‐doped sample showed peaks at 356, 430, and 583 K and its intensity sublinearly increased up to 90 min and then thereafter decreased. The TL trapping parameters were calculated using computerized glow curve deconvolution methods. The Li⁺ co‐doped sample exhibited less fading and high trap density under the UV radiation.     

Zwitterion l-cysteine adsorbed on the Au20 cluster: enhancement of infrared active normal modes

The study reported herein addressed the structure, adsorption energy and normal modes of zwitterion l-cysteine (Z-cys) adsorbed on the Au₂₀ cluster by using density functional theory (DFT). It was found that four Z-cys are bound to the Au₂₀ apexes preferentially through S atoms. Regarding normal modes, after adsorption of four Z-cys molecules, a more intense infrared (IR) peak is maintained around 1,631.4 cm^?1 corresponding with a C=O stretching mode, but its intensity is enhanced approximately six times. The enhancement in the intensity of modes between 0 to 300 cm^?1 is around 4.5 to 5.0 times for normal modes that involve O–C=O and C-S bending modes. Other two normal modes in the range from 300 to 3,500 cm^?1 show enhancements of 6.0 and 7.4 times. In general, four peaks show major intensities and they are related with normal modes of carboxyl and NH₃ groups of Z-cys.     

Kinetic and Vibrational Isotope Effects of Proton Transfer Reactions in Channelrhodopsin-2

Channelrhodopsins (ChRs) are light-gated cation channels. After blue-light excitation, the protein undergoes a photocycle with different intermediates. Here, we have recorded transient absorbance changes of ChR2 from Chlamydomonas reinhardtii in the visible and infrared regions with nanosecond time resolution, the latter being accomplished using tunable quantum cascade lasers. Because proton transfer reactions play a key role in channel gating, we determined vibrational as well as kinetic isotope effects (VIEs and KIEs) of carboxylic groups of various key aspartic and glutamic acid residues by monitoring their C=O stretching vibrations in H₂O and in D₂O. D156 exhibits a substantial KIE (>2) in its deprotonation and reprotonation, which substantiates its role as the internal proton donor to the retinal Schiff base. The unusual VIE of D156, upshifted from 1736 cm⁻¹ to 1738 cm⁻¹ in D₂O, was scrutinized by studying the D156E variant. The C=O stretch of E156 shifted down by 8 cm⁻¹ in D₂O, providing evidence for the accessibility of the carboxylic group. The C=O stretching band of E90 exhibits a VIE of 9 cm⁻¹ and a KIE of ∼2 for the de- and the reprotonation reactions during the lifetime of the late desensitized state. The KIE of 1 determined in the time range from 20 ns to 5 ms is incompatible with early deprotonation of E90.     

Chemical alterations of hyaluronic acid and dermatan sulfate detected in aging human skin by infrared spectroscopy

Age-mediated deacetylation of hyaluronic acid and dermatan sulfate, and shift of sulfate ester configuration were indicated by infrared spectroscopy. Hyaluronic acid and the three dermatan sulfates (DS₁₈, DS₁₈ and DS₃₅), sequentially precipitated from adult skin with 18%, 28% and 35% ethanol, were analyzed at varying ages. At age 75 years, loss of infrared bands in the 1650-1600 cm⁻¹ region, at 1380 cm⁻¹ and 1320 cm⁻¹ and appearance of a band at 1560 cm⁻¹ were characteristic of hyaluronic acid and DS₃₅,·moreover, in DS₂₈ and DS₃₅ the intensities of the bands at 840 cm⁻¹ and 860 cm⁻ were, respectively, decreased and increased. A low intensity band in the 805-785 cm⁻¹ region was observed in the spectra of DS₁₈ (19–35 years), DS₂₈ (70–80 years) and DS₃₅ (all ages). It intensified in DS₂₈ of the 80-years-olds. In the 75±5-year-old group. ninhydrin-positive material of hyaluronic acid and DS₃₅ increased, while reducing GlcNAc of hyaluronic acid decreased. The data demonstrated hyaluronic acid and DS₃₅ deacetylation and suggested a decrease of equatorial sulfates with infrared band at 840 cm⁻¹ and an incrase of axial sulfates with band at 860 cm⁻¹ in DS₂₈ and DS₃₅ of the 75±5-yearl-old set. Equatorial sulfates with band in the 805±785 cm⁻¹ region apparently decreased in DS₁₈ after 35 years and increased in DS₂₈ of the oldest group.     

Evidence for light-induced 13-cis, 14-s-cis isomerization in bacteriorhodopsin obtained by FTIR difference spectroscopy using isotopically labelled retinals

We have obtained by Fourier transformed infra-red (FTIR)-spectroscopy BR-K, BR-L and BR-M difference spectra of bacteriorhodopsin regenerated with isotopically labelled retinals. Thereby, we are able to assign reliably the C₁₄–C₁₅ and C=N stretching vibrations of the various intermediates. The lower C₁₄–C₁₅ stretching vibration frequency in L as compared with 13-cis protonated Schiff base model compounds indicates a 13-cis, 14-s-cis configuration of the retinal in this species. The unusually low C=N stretching vibration in K at 1615 cm⁻¹ indicates less stabilization of the positive charge at the Schiff base by the protein environment. Based on these results, a mechanism is suggested by which the stored light energy is transformed into proton transfers.     

A vibrational spectroscopic study of the self-association of 5′-GMP in aqueous solution

The Raman spectra of highly concentrated solutions of 5′-GMP at neutral and acid pH were recorded in order to better characterize the structure of the self-aggregates formed in these solutions and their melting behavior. Vibrational coupling of the C?O stretching vibrations in tetrameric units at neutral pH is shown to yield a characteristic pattern of two Raman bands at ca. 1730 and 1680 cm^?1 (1708 and 1664 cm^?1 in D₂O), and an iractive mode at 1678 cm^?1 in D₂O. From the intensity of the 1730-cm^?1 band, proportional to tetramer concentration, and that at 1485 cm^?1, which reflects the stacking of the bases, the thermal stability of the self-associates formed at neutral pH is shown to be higher for stacked tetramers. At acid pH, the melting of the helical aggregates responsible for the formation of a gel is preceded by the freeing of the hydrogen-bonded phosphate groups, accompanied by a change of conformation from C3′-endo to C2′-endo in some of the associated ribose units. Previous spectroscopic results suggesting the formation of tetramers as an intermediate step in the melting of the gel were not reproduced in this study.     

Structural and Mechanistic Analysis of the Choline Sulfatase from Sinorhizobium melliloti: A Class I Sulfatase Specific for an Alkyl Sulfate Ester

Hydrolysis of organic sulfate esters proceeds by two distinct mechanisms, water attacking at either sulfur (S–O bond cleavage) or carbon (C–O bond cleavage). In primary and secondary alkyl sulfates, attack at carbon is favored, whereas in aromatic sulfates and sulfated sugars, attack at sulfur is preferred. This mechanistic distinction is mirrored in the classification of enzymes that catalyze sulfate ester hydrolysis: arylsulfatases (ASs) catalyze S–O cleavage in sulfate sugars and arylsulfates, and alkyl sulfatases break the C–O bond of alkyl sulfates. Sinorhizobium meliloti choline sulfatase (SmCS) efficiently catalyzes the hydrolysis of alkyl sulfate choline-O-sulfate (k_cat/K_M = 4.8 × 10³ s^? 1 M^? 1) as well as arylsulfate 4-nitrophenyl sulfate (k_cat/K_M = 12 s^? 1 M^? 1). Its 2.8-Å resolution X-ray structure shows a buried, largely hydrophobic active site in which a conserved glutamate (Glu386) plays a role in recognition of the quaternary ammonium group of the choline substrate. SmCS structurally resembles members of the alkaline phosphatase superfamily, being most closely related to dimeric ASs and tetrameric phosphonate monoester hydrolases. Although > 70% of the amino acids between protomers align structurally (RMSDs 1.79–1.99 Å), the oligomeric structures show distinctly different packing and protomer–protomer interfaces. The latter also play an important role in active site formation. Mutagenesis of the conserved active site residues typical for ASs, H₂¹⁸O-labeling studies and the observation of catalytically promiscuous behavior toward phosphoesters confirm the close relation to alkaline phosphatase superfamily members and suggest that SmCS is an AS that catalyzes S–O cleavage in alkyl sulfate esters with extreme catalytic proficiency.     

Sensing Biophysical Alterations of Human Lung Epithelial Cells (A549) in the Context of Toxicity Effects of Diesel Exhaust Particles

Diesel exhaust particles (DEP) in urban air are associated with numerous respiratory diseases. The role of underlying biomechanics in cytotoxicity of individual lung cells relating to DEP exposure is unclear. In this study, atomic force microscopy (AFM), confocal Raman microspectroscopy (RM), and fluorescence (FL) microscopy were used to monitor alterations of single A549 cells exposed to DEP. Results revealed a significant decrease in membrane surface adhesion force and a significant change in cell elasticity as a function of DEP–cell interaction time, and the dynamic changes in cellular biocomponents which were reflected by changes of characteristic Raman bands: 726 cm^?1 (adenine), 782 cm^?1 (uracil, cytosine, thymine), 788 cm^?1 (O–P–O), 1006 cm^?1 (phenylalanine), and 1320 cm^?1 (guanine) after DEP exposure. These findings suggest that the combination of multi-instruments (e.g., AFM/FL) may offer an exciting platform for investigating the roles of biophysical and biochemical responses to particulate matter-induced cell toxicity.     

Characteristics of activated carbon remove sulfur particles against smog

Sulfur particles, which could cause diseases, were the main powder of smog. And activated carbon had the very adsorption characteristics. Therefore, five sulfur particles were adsorbed by activated carbon and were analyzed by FT-IR. The optimal adsorption time were 120 min of Na₂SO₃, 120 min of Na₂S₂O₈, 120 min of Na₂SO₄, 120 min of Fe₂(SO₄)₃ and 120 min of S. FT-IR spectra showed that activated carbon had the eight characteristic absorption of SS stretch, H₂O stretch, OH stretch, CH stretch, conjugated CO stretch or CC stretch, CH₂ bend, CO stretch and acetylenic CH bend vibrations at 3850 cm^–1, 3740 cm^–1, 3430 cm^–1, 2920 cm^–1, 1630 cm^–1, 1390 cm^–1, 1110 cm^–1 and 600 cm^–1, respectively. For Na₂SO₃, the peaks at 2920 cm^–1, 1630 cm^–1, 1390 cm^–1 and 1110 cm^–1 achieved the maximum at 20 min. For Na₂S₂O₈, the peaks at 3850 cm^–1, 3740 cm^–1 and 2920 cm^–1 achieved the maximum at 60 min. The peaks at 1390 cm^–1, 1110 cm^–1 and 600 cm^–1 achieved the maximum at 40 min. For Na₂SO₄, the peaks at 3430 cm^–1, 2920 cm^–1, 1630 cm^–1, 1390 cm^–1, 1110 cm^–1 and 600 cm^–1 achieved the maximum at 60 min. For Fe₂(SO₄)₃, the peaks at 1390 cm^–1, 1110 cm^–1 and 600 cm^–1 achieved the maximum at 20 min. For S, the peaks at 1630 cm^–1, 1390 cm^–1 and 600 cm^–1 achieved the maximum at 120 min. It provided that activated carbon could remove sulfur particles from smog air to restrain many anaphylactic diseases.     

Study of hydrogen bonds in cyrstalline monosaccharides the spectra of monosaccharides derivatives in the middle-and far-infrared regions

The spectra of a series of monosaccharide derivatives in the middle- and far-infrared region were investigated. An explanation is provided for the band shifts in the OH stretching region at 3100–3400 cm^?1 and in the region of hydrogen-bond vibrations at 180–120 cm^?1 under effect of low temperatures. A comparison of i.r., X-ray, and neutronographic data indicates the absence of intramolecular hydrogen-bonds in the crystalline monosaccharide derivatives investigated.     

The influence of malignancy processes in pancreatic tissue on the formation of optical and infrared spectra in bile and pancreatic juice samples

The results of optical spectral studies in the wavelength range of 250–1500 nm and frequencies of 6000–400 cm^–1 of samples of bile and pancreatic juice with the development of malignancy in the tissues of the pancreas are presented. It was shown that the development of degenerative processes in the studied biological fluids led to an increase in the intensity of the spectral profile of absorption at low frequencies (1600–400 cm^–1) and the appearance of a peak near the frequency of 840 ± 5 cm^–1 formed by the vibrations of the O–O groups of aliphatic and aromatic peroxides or peroxide acids. It was demonstrated that the development of malignant processes led to an increase and to a decrease of the density and size of particles in the samples of bile and pancreatic juice, respectively, as inferred from the corresponding increase and decrease of the coefficients of absorption and scattering of light.     

Laser-Raman study of valinomycin-doped and omega-CD3-labeled phosphatidylcholine liposomes

The relative intensities of the CH stretching vibrations are used to study the interaction of lecithin liposomes with valinomycin, a mobile carrier for alkali ions. In the case of dipalmitoyl lecithin liposomes, the lipid phase transition is not significantly affected by valinomycin. However, in dimyristoylphosphatidylcholine liposomes, the phase transition is broadened by the addition of 1 mol% valinomycin even at low K⁺ concentrations. This indicates that the carrier interacts with the hydrophobic core of the bilayer. In addition, these experiments showed that the lipid phase transitions which are reflected by the methylene groups and the terminal methyl groups are nearly equivalent. Therefore a reevaluation of the assignment of the CH stretching bands seemed necessary. Our Raman spectroscopic investigation of ω-deuterated dipalmitoyl lecithin liposomes improves the assignment of CH stretch vibrations to methylene and methyl groups. The deuteration displaces the methyl group vibrations to the 2050–2250 cm^?1 region and produces gross intensity changes of the bands at 2883 and 2936 cm^?1. These changes lead to the conclusion that both bands arise from vibrations which can be attributed simultaneously to the methylene and methyl groups of the fatty acid chains. The displacement of the CH₃ group vibrations from their original positions enhances the intensity ratios (per centimeter), $\text{2883}\text{2847}$ and $\text{2936}\text{2847}$, for the CH₂- groups which are used to monitor the lipid phase transition, and implies that the contributions of the CH₃ groups to the phase transition curves are unimportant. Our finding that the -CD₃ groups reflect no phase transition supports this statement.